1. Field of the Invention
The disclosure relates generally to a boosting method, and more particularly relates to a boosting circuit of a semiconductor device memory such as a semiconductor memory which requires a high voltage.
2. Description of the Related Art
Along with the miniaturization of the semiconductor design, the required operation voltage for driving semiconductor elements has decreased, and the required power voltage provided to the semiconductor device has decreased accordingly. For example, the power voltage provided from an external device to a semiconductor memory, has decreased from 3.3-2.5V to 1.8V. Also, the inner circuit of a semiconductor memory usually requires, multiple power voltages, for example, the voltage for driving the transistor or the voltage applied to the wells, etc., so that it requires a high voltage higher than the power voltage. Thus, the semiconductor device requires a boosting circuit to boost the supply voltage supplied from the external device to a desired voltage. This boosting circuit is typically formed by a charge pump circuit.
As show in FIG. 1, Patent Document 1 discloses two pump circuits connected in series constituting a boosting circuit which may boost the power voltage to a value that is more than twice as high as before. This boosting circuit is applied to an inner circuit of a dynamic memory, and transforms the power voltage VDD into a higher voltage Vpp which is applied to a word line. The boosting circuit comprises an inverter INV, capacitors C1, C2, and switches SW1, SW2. As shown in FIG. 1a, when the switches SW1, SW2 are turned off, the negative electrode of the capacitor C1 is connected with the ground, the capacitor C1 accumulates the charges corresponding to the power supply VDD, and the capacitor C2 also accumulates the charges corresponding to the power supply VDD.
When the driving voltage Vpp is applied to a word line of a DRAM, the switches SW1, SW2 are turned on, and the electrode of the capacitor C1 is boosted to 2*VDD from VDD and the electrode of the capacitor C2 is boosted to 3*VDD and the boosting voltage Vpp is applied to the word line.
Also, considering that the timing of operating the boosting circuit in the semiconductor device and the timing of the boosting voltage being consumed does not match, and it is difficult to speed up the boosting speed of the charge pump circuit, so that it usually makes a plurality of the boosting circuits distributed to work. Patent Document 2 has disclosed a boosting circuit is capable to consume a matching timing to obtain a better efficiently.